Alpha-smooth muscle actin and the modulation of endothelial and epithelial cell biology

Fri, 09/16/2016 - 14:36

Actin is essential for a wide range of cell functions, ranging from cell division and chromatin remodeling to vesicle trafficking and maintenance of cellular structure. In fact, mislocalization of actin to cell junctions during development leads to facial malformations such as cleft lip.  Actin is successful in the regulation of a variety of cell functions due to its high number of isoforms.  One such isoform of actin is alpha-smooth muscle actin (alpha-SMA), which is plentiful in vascular smooth-muscle cells and plays an important role in fibrogenesis and fibrosis (the thickening of tissue). There are distinct phenotypes associated with a lack of alpha-SMA during and after development.  Studies have shown that mutated alpha-SMA during development results in disarray of cardiac muscles and intense muscle weakness in young rodent infants.  In adults, mutations in smooth muscle actin can lead to cardiac and blood pressure complications. 

alpha smooth muscle actin antibody

Immunohistochemistry-Paraffin: alpha-Smooth Muscle Actin Antibody [NB600-531] - Human small intestine stained with anti-alpha-smooth muscle Actin antibody.

Stawski et al used an alpha-SMA antibody in their research on angiotensin II and its role in inducing epithelial skin fibrosis.  Specifically, Stawksi et al focused on systemic sclerosis (SSc), which is an autoimmune disease characterized by early vascular insufficiency.  Because of the role of vascular insufficiency in SSc, Angiotensin II, a vasoactive peptide involved in vascular constriction, was a target of their study.  First, angiotensin II was administered at a rate of 1,000 ng/kg/min to 8-week-old male mice to determine the level of collagen synthesis and induction.  After 14 days the mice did in fact show dermal fibrosis in reaction to the angiotensin II application.  Next, an alpha-SMA antibody was used to investigate whether angiotensin II activates the TGF-Beta pathway, which activates fibroblasts.  The alpha-SMA antibody was used in immunohistochemical analysis and showed a positive staining in angiotensin II treated mice.  Further studies using an alpha-SMA antibody revealed that angiotensin II increases the number of myofibroblasts in mouse skin, and that alpha-SMA mRNA levels were elevated in this model (as measured by RT-PCR). 

Contrary to an epithelial cell study, Tate et al used an alpha-SMA antibody as part of their GSLC xenografts in order to elucidate the potential role of BMP7 in inhibiting tumor angiogenesis via modulation of endothelial cell biology.  As mentioned prior, alpha-SMA is activated downstream of the TGF-beta pathway, and bone morphogenetic proteins (BMPs) are TGF-beta family members.  Tate et al used four-week-old nude mice in order to take a closer look at the role of BMP7 in VEGF, bFGF, and tumor driven angiogenesis.  Treatment with BMP7 was introduced one week after grafting occurred.  The alpha-SMA antibody was used in immunohistochemistry on these grafts and revealed that BMP7 treatment reduced VEGF, bFGF and Matrigel driven cord formation.  This result was determined by the lack of connected tube area in the grafted tissue versus the PBS control tissue.   

Novus Biologicals offers alpha-Smooth Muscle Actin reagents for your research needs including:

PMID: 25919028
PMID: 22913887
PMID: 20737541

Blog Topics